["Corporate Social Responsibility and Environmental Management, EarlyView. ", "\nABSTRACT\nMotivated by the growing importance of environmental, social, and governance (ESG) performance in emerging markets, we examine how family control and ownership, together with corporate culture, influence the ESG performance of publicly listed firms in Thailand. We find that family control and corporate culture have positive impacts on ESG performance, whereas pure family ownership has a muted effect. A one‐standard deviation increase in corporate culture is associated with a 46% increase in ESG performance, while family control with at least 20% ownership stakes is associated with a 14% increase. Further, findings show, supporting the stewardship hypothesis, corporate culture strengthens family control's ESG benefits, while consistent with the expropriation hypothesis, it has a muted effect on pure family control's ESG link. As ESG performance is linked to firm competitiveness, our findings highlight family control with ownership stakes and corporate culture as key determinants of corporate sustainability, with implications for governance design and responsible investment.\n"]